From the " Dirty Dozen " watches which are Eterna, Omega, JLC, IWC, Longines, Cyma, Buren, Lemania, Timor, Record, Vertex, the Grana is the rarest one, with much less than 5000 watches made. Some say around 1000, compared to the 25, 000 pieces made by Omega and Record.
Hence the fact that the Grana reaches some heavy prices...
Here is a nice one, which was auctioned by Sothebys. 35 mm case.

These military watches are really bewitching.
Best,
Nicolas